Electronic device housing

ABSTRACT

An electronic device housing is described that includes a substantially flat support plate comprising a composite material and an edge frame comprising a foam material. The edge frame is coupled to the support plate at a perimeter of the support plate and defines a cavity. One or more electronic components may be disposed in the cavity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/609,135, filed on Sep. 10, 2012, and hereby incorporated by referencein its entirety.

BACKGROUND

A large and growing population of users enjoy entertainment through theconsumption of digital media items, such as music, movies, images,electronic books and so on. Users employ various electronic devices toconsume such media items. Among these electronic devices are electronicbook readers, cellular telephones, personal digital assistants (PDAs),portable media players, tablet computers, netbooks and the like.

These electronic devices often include a housing to protect internalelectrical components of the electronic device. It can be difficult todesign a housing that is both light and strong.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detaileddescription given below and from the accompanying drawings of variousembodiments of the present invention, which, however, should not betaken to limit the present invention to the specific embodiments, butare for explanation and understanding only. Further, it should beunderstood that the drawings are not necessarily proportional or toscale.

FIG. 1 illustrates an exploded perspective view of an embodiment of anelectronic device housing.

FIG. 2 illustrates a front view of an embodiment of an electronicdevice.

FIG. 3 illustrates a rear view of an embodiment of an electronic device.

FIG. 4 illustrates a front view of an embodiment of an edge frame of anelectronic device housing.

FIG. 5 illustrates a cross-sectional side view of an embodiment of anelectronic device housing.

FIG. 6 illustrates a cross-sectional side view of an embodiment of anelectronic device.

FIG. 7 illustrates a cross-sectional side view of an embodiment of anelectronic device housing having an edge frame composed of multiplematerials.

FIG. 8 illustrates a cross-sectional side view of an embodiment of anelectronic device housing having a device-spanning support plate.

FIG. 9 illustrates a cross-sectional side view of an embodiment of anelectronic device housing having an edge frame with flat externalsurfaces.

FIG. 10 illustrates a cross-sectional view of an embodiment of anelectronic device housing having a support plate and a rear cover.

FIG. 11 illustrates a flowchart of a method of forming an electronicdevice.

DETAILED DESCRIPTION

Embodiments of an electronic device housing having a low-density edgeframe coupled with a high-stiffness support plate are described. Forexample, the edge frame may be composed of aluminum foam. Because thealuminum foam comprises aluminum, it provides the look and feel ofaluminum. For example, like solid aluminum, the exterior surface of analuminum foam edge frame has a metallic sheen and feels smooth and coolto the touch. However, the density of the aluminum foam is much lessthan solid aluminum. For example, aluminum foam may have a density of0.6 grams per cubic centimeter (g/cc), whereas solid aluminum may have adensity of 2.70 g/cc. Even though aluminum foam is low-density, it isstill relatively stiff for its weight. In particular, the elasticmodulus (sometimes referred to as Young's modulus) even exceeds that ofpolymers with higher density. For example, aluminum foam may have anelastic modulus of 4 to 5 gigapascals (GPa), whereas polymers with adensity of 1.0 g/cc may only have an elastic modulus of 1 to 2 GPa. Thesupport plate significantly increases the stiffness of the housing. Thesupport plate may be composed of a composite material, such acarbon-fiber reinforced polymer or aluminum metal matrix composite. Eachof these materials has a very high elastic modulus (between 65 and 150GPa), but are also relatively low-density for their stiffness (between2.0 g/cc and 3.5 g/cc). Combined, the edge frame and the support plateform a housing that is both lightweight and stiff.

FIG. 1 illustrates an exploded perspective view of an embodiment of anelectronic device housing 101. The housing 101 includes an edge frame110, a front cover 120, and a support plate 130. The edge frame 110 isillustrated with dashed lines to ease understanding of the perspectiveview.

When assembled, the front cover 120 rests upon a front bezel 117 of theedge frame 110 and is surrounded by the edge frame 110. The edge frame110 may be also have a rear bezel 119 (not visible in the perspectiveview, but illustrated in, e.g. FIG. 5) upon which the support plate 130rests. In one embodiment, the support plate 130 is also surrounded bythe edge frame 110 when the support plate 130 rests on the rear bezel119.

Whereas the front cover 120 and the support plate 130 are relativelythin, the edge frame 110 provides thickness to the housing 101. The edgeframe 110 may be a lightweight material. For example, the edge frame 110may have a density of less than 1.0 grams g/cc. As another example, theedge frame 110 may have a density of less than 0.8 g/cc, less than 0.6g/cc or less than 0.5 g/cc. Thus, although the edge frame 110 providesthickness to the housing 101, it does not add substantial weight to thehousing 101.

In one embodiment, the edge frame 110 is composed of foam. Inparticular, the edge frame 110 may be composed of metal foam, such asaluminum foam, magnesium foam or titanium foam. The edge frame 110 maybe composed of other types of foam, such as cellulose foam, polymerfoam, or styrene foam. The foam may be open-celled or closed-celled. Thefoam may be a reticulated foam or a syntactic foam. In one embodiment,the edge frame 110 is composed of a closed-cell aluminum foam having anaverage cell size of approximately 0.5 millimeters (mm) or less.Although aluminum foam may be advantageous because of its low density ascompared to other materials, aluminum foam is also advantageous becauseof its relative stiffness in view of its lightweight. For example,aluminum foam is less dense than the lightest metals used in consumerelectronic housings and is even less dense than polymer materials.Nevertheless, at this lower density, aluminum foam provides morestiffness than polymer materials. In particular, the elastic modulus ofaluminum foam may exceed two or three times that of polymer materialsunless the polymer is heavily infused with glass (and, therefore, moredense). Although the edge frame may be composed of aluminum foam, it isto be appreciated that the edge frame 110 may be composed of solidmetal, plastic, glass or any other material.

The front cover 120 may be composed of glass. The front cover 120 may bealso be composed of plastic or any other material. The front cover 120may comprise a screen which can display text, images or other media. Thescreen may comprise a liquid crystal display (LCD), an electronic paperdisplay, or any another type of display. For example, an electronicpaper display may comprise a bi-stable LCD display, amicroelectromechanical system (MEMS) display, a cholesteric display, anelectrophoretic display, or another electronic paper display. Oneexemplary electronic paper display that may be used is an E Ink-branddisplay. The front cover 120 may also comprise a touchpad which canreceive input from a user. In one embodiment, the front cover 120comprises a touchscreen.

In one embodiment, the support plate 130 is, like the front cover 120,surrounded by the edge frame 110. Whereas the edge frame 110 may be alightweight material and may not provide enough stiffness and durabilityto the housing 101 to prevent deformation during rigorous consumer use,the support plate 130 provides additional stiffness to the housing 101.For example, the support plate 130 may have an elastic modulus of 50gigapascals (GPa) or greater. As another example, the support plate 130may have an elastic modulus that is 90 GPa or greater.

For comparison, it is noted that the elastic modulus of aluminum foammay be between 4 and 10 GPa. Thus, the support plate 130 may have anelastic modulus that is much higher than the edge frame 110. However,the support plate 130 may also have a density that is greater than thatof the edge frame 110. For example, the density of aluminum foam may bebetween 0.4 g/cc and 0.8 g/cc, whereas the support plate 130 may have adensity between 1.5 g/cc and 2.5 g/cc or higher.

In one embodiment, the support plate 130 is composed of a compositematerial. In one embodiment, the support plate 130 is composed of fiberreinforced polymer, such as glass-fiber reinforced polymer (GFRP),carbon-fiber reinforced polymer (CFRP) or aramid-fiber reinforcedpolymer (AFRP). The aramid-fiber may include Kevlar, Twaron, Nomex,para-aramids, or other materials. In another embodiment, the supportplate 130 is composed of a metal matrix composite, such as aluminummetal matrix composite (Al-MMC), magnesium metal matrix composite(Mg-MMC), titanium metal matrix composite (Ti-MMC) or copper metalmatrix composite (Cu-MMC). The support plate 130 may be composed ofother composite materials or other non-composite materials.

FIG. 2 illustrates a front view of an embodiment of an electronic device100. FIG. 3 illustrates a rear view of the electronic device 100. Theelectronic device 100 may include an electronic book reader, a cellulartelephone, a personal digital assistant (PDAs), a portable media player,a tablet computer, a netbook or any portable, compact electronic device.

The electronic device 100 includes a housing 101 that houses andprotects a number of internal electronic components that provide variousfunctionality to the electronic device 100. The housing 101 includes anedge frame 110, a front cover 120, and a support plate 130 as describedabove with respect to FIG. 1. The edge frame 110 is illustrated as afoam having a number of cells. In one embodiment, the foam is anopen-celled foam. In another embodiment, the foam is a closed-cell foam.Although the FIGS. illustrate cells of a particular size, shape,density, and distribution it is to be appreciated that the drawings arenot necessarily to scale and that the cells of the foam may be any size,shape, density, or distribution.

FIG. 4 illustrates a front view of an embodiment of an edge frame 110 ofan electronic device housing 101. The edge frame 110 includes a recessedfront bezel 117 upon which the front cover 120 is set. Although notvisible from the front view of FIG. 3, but visible from thecross-section of FIG. 5, the edge frame 110 may further comprise arecessed rear bezel 119 upon which the support plate 130 is set.

Although the edge frame 110 of FIG. 4 is illustrated as a closedrectangular shape with rounded corners, other shapes are possible. Forexample, the edge frame 110 may be any closed shape, such as a square, acircle, a triangle or an irregular shape. The edge frame 110 may havesharp or rounded corners. The edge frame 110 may be an open shape, suchas a U-shape which only surrounds the front cover 120 on three sides.The edge frame 110 may be composed of multiple discontinuous regions.For example, the edge frame 110 may have four portions that surround thefront cover 120 on four sides, but not at the corners. The edge frame110 may be any shape.

FIG. 5 illustrates a cross-sectional side view of the housing 101. Thehousing 101 includes an edge frame 110 that couples and defines a cavity140 between a front cover 120 and a support plate 130. The edge frame110 includes a front bezel 117 upon which the front cover 120 is set anda rear bezel 119 upon which the support plate 130 is set.

FIG. 6 illustrates a cross-sectional side view of an embodiment of anelectronic device 100. The electronic device 100 includes the housing101 of FIG. 5 and electronic components disposed within the cavity 140defined by the housing 101. The electronic components may include, forexample, a printed circuit board (PCB) 150 having components 151disposed thereon and coupled by one or more conductive traces 152. Thecomponents 151 may include, for example, a resistor, a switch, a diode,a battery, a processor, a memory or any of other component.

FIG. 6 also illustrates certain dimensions of the housing components. Inparticular, a thickness (T_(s)) of the front cover 120, a thickness(T_(s)) of the support plate 130, a width (W_(s)) of the support plate130, a thickness (T_(F)) of the edge frame 110 and a width (W_(F)) ofthe edge frame 110 are shown.

In one embodiment, the support plate 130 is fundamentallytwo-dimensional. For example, the width (W_(s)) of the support plate 130may be much greater than the thickness (T_(s)) of the support plate 130.As an example, the width (W_(s)) may be at least 10 times greater thanthe thickness (T_(s)). As an example, the width (W_(s)) may be at least50 times greater than the thickness (T_(s)). As another example, thewidth (W_(s)) may be at least 100 times greater than the thickness(T_(s)). In one embodiment, the thickness (T_(s)) of the support plate130 may be 1.0 mm or less. In one embodiment, the thickness (T_(s)) maybe 0.6 mm or less. In one embodiment, the thickness (T_(s)) may be 0.5mm or less.

In contrast to the thinness of the support plate 130, the edge frame 110may be relatively thick. For example, the thickness (T_(F)) of the edgeframe 110 may be at least 10 times greater than the thickness (T_(s)) ofthe support plate 130. As another example, the thickness of the edgeframe 110 may be at least 20 times greater than the thickness (T_(s)) ofthe support plate 130.

In contrast to the flatness of the support plate 130, the edge frame 110may be fundamentally three-dimensional. For example, the width (W_(F))of the edge frame 110 may be the same order of magnitude as thethickness (T_(F)) of the edge frame 110. As an example, the thickness(T_(F)) of the edge frame 110 may be greater than a quarter the width(W_(F)) of the edge frame 110. As another example, the thickness (T_(F))of the edge frame 110 is greater than half the width (W_(F)) of the edgeframe 110. In one embodiment, the thickness (T_(F)) of the edge frame110 is greater than the width (W_(F)) of the edge frame 110. In oneembodiment, the thickness (T_(F)) of the edge frame 110 is greater thantwice the width (W_(F)) of the edge frame 110. In one embodiment, thethickness (T_(F)) and width (W_(F)) of the edge frame may be betweenapproximately 5 mm and 10 mm. In one embodiment, the thickness (T_(F))of the edge frame is at least five times the thickness (T_(s)) of thesupport plate.

The front cover 120 may also be fundamentally two-dimensional, butthicker than the support plate 130. For example, the thickness (T_(C))of the front cover 120 may be greater than 5 times the thickness (T_(s))of the support plate 130. As another example, the thickness (T_(C)) ofthe front cover 120 may be greater than 10 times the thickness (T_(s))of the support plate 130. In one embodiment, the thickness (T_(C)) ofthe front glass is approximately 3 mm.

The support plate 130 is, in one embodiment, composed of a stiffcomposite material. Thus, the support plate 130 provides strength anddurability to the housing 101. However, the composite material may bedifficult to form into non-flat or fundamentally three-dimensionalshapes. Thus, in one embodiment, the edge frame 110 is composed of foam.A foam edge frame 110 provides thickness to the housing 101 withoutsubstantial additional weight. In comparison to the support plate 130,the edge frame 110 may not be stiff. However, in conjunction with thesupport 130, the edge frame 110 forms a housing 101 that is strong,durable and lightweight.

As compared to each other, the support plate 130 may be relatively flatand stiff and the edge frame 110 may be relatively non-flat anddeformable. For example, the support plate 130 may have an elasticmodulus that is at least 5 times greater than the elastic modulus of theedge frame 110. As another example, the support plate 130 may have anelastic modulus that is at least 10 times greater than the elasticmodulus of the edge frame. As another example, the support plate 130 mayhave an elastic modulus that is at least 20 times greater than theelastic modulus of the edge frame. For example, as noted above, theelastic modulus of the support plate 130 may be 50 GPa or greater or 90GPa or greater.

In one embodiment, the edge frame 110 is less dense than the supportplate 130. For example, the density of the edge frame 110 may be lessthan half the density of the support plate 130 or less than a quarterthe density of the support plate 130.

As mentioned above, the edge frame 110 and support plate 130 may becomposed of glass, plastic, metal, foam, composite materials or anyother kind of material. Properties of various materials that could beused for the edge frame 110 and support plate 130 are discussed below.Different materials provide different weight and stiffness to thehousing 101. In one embodiment the edge frame 110 and support plate 130are composed of different materials. By using different materials forthe edge frame 110 and the support plate 130, a housing 101 that is bothlightweight and durable can formed. In other embodiments, the edge frame110 and support plate 130 may be formed of the same material. In oneembodiment, the edge frame 110 and support plate 130 are formed as onepiece, a single piece of homogenous material.

Closed-cell aluminum foam having a cell size of approximately 0.5 mm canbe formed with a density between 0.4 g/cc and 0.8 g/cc with an elasticmodulus between 4 and 10 GPa. Polymers may be formed with a density ofapproximately 1.0 g/cc with an elastic modulus of about 1 to 2 GPa.Solid magnesium has a density of approximately 1.74 g/cc and an elasticmodulus of approximately 45 GPa. Solid aluminum has a density ofapproximately 2.70 g/cc and an elastic modulus of approximately 70 GPa.Steel has a density between approximately 7.75 g/cc and 8.05 g/cc and anelastic modulus between approximately 200 GPa. Thus, closed-cellaluminum foam can be formed with a density that is less than a polymermaterial, while still providing an elastic modulus that is at least twoto three times greater. Although closed-cell aluminum foam has anelastic modulus that is much less than other metals, it is also muchless dense.

Plastic may be formed with a density of approximately 1.1 g/cc with anelastic modulus of about 2 GPa. Plastic may also be formed with adensity of approximately 1.5 g/cc with an elastic modulus between 15 GPaand 20 GPa. Glass has a density between 2 g/cc and 3 g/cc and has anelastic modulus between 50 and 90 GPa. Thus, aluminum foam can be formedwith a density that is less than lightweight plastic, while stillproviding an elastic modulus that is at least two to three timesgreater. Although closed-cell aluminum foam has an elastic modulus thatis less than heavy plastic or glass, it is also less dense.

Aramid-fiber reinforced polymer material may be formed with a density ofapproximately 1.5 g/cc and an elastic modulus between 30 and 35 GPa.Carbon-fiber reinforced polymer material may be formed with a density ofapproximately 2.0 g/cc and an elastic modulus between approximately 65and 70 GPa. Glass-fiber reinforced polymer material may be formed with adensity of approximately 2.5 g/cc and an elastic modulus betweenapproximately 70 GPa and 90 GPa. Aluminum metal matrix compositematerial may be formed with a density of approximately 2.8 g/cc and anelastic modulus between approximately 100 GPa and 150 GPa. Compositematerials, such as those described above, although more dense than,e.g., aluminum foam, each provides a much higher elastic modulus.Further, as compared to other materials with a high elastic modulus,such as steel, the density is much less.

FIG. 7 illustrates a cross-sectional side view of an embodiment of anelectronic device housing 201 having an edge frame 210 composed ofmultiple materials. The housing 201 is substantially similar to thehousing 101 of FIG. 4; however, the edge frame 210 includes an interiorportion composed of an interior material 112 and an exterior portioncomposed of an exterior material 114. The interior material 112 may be alow-density material, such as foam, whereas the exterior material 114may provide desired aesthetic properties. For example, the exteriormaterial 114 may be a finishing film or chrome. In another embodiment,the interior material 112 and the exterior material 114 may be the samesubstance with different properties. For example, the interior material112 may be aluminum foam and the exterior material 114 may be a skin ofsolid aluminum. Such an edge frame 210 may be created using a powdermetallurgy process in which aluminum powder is mixed with a foamingagent, placed into a three-dimensional mold, heated and compressed. Thecompression creates a casting skin having different properties than thematerial interior to the mold.

The exterior material 114 may provide a smooth outer surface not presentin the interior material 112. For example, as shown in FIG. 7, theinterior material 112, as an open-celled or closed-celled foam, mayinclude cells that intersect the outer edge of the interior material 112resulting in surface irregularities. The exterior material 114 may coverthese irregularities.

Although, illustrated as such in FIG. 7, the exterior material 114 neednot completely cover the interior material 112. In one embodiment, theexterior material 114 comprises less than 10% of the edge frame 210. Inone embodiment, the exterior material is less than 1 mm thick.

FIG. 8 illustrates a cross-sectional side view of an embodiment of anelectronic device housing 301 having a device-spanning support plate330. The housing 301 is substantially similar to the housing 101 of FIG.4; however, the support plate 330 spans the entire rear of the housing301. Thus, rather than being set on a rear bezel of the edge frame 310,the support plate 330 is attached to the rear of the edge frame 310.Further, rather than being surrounded by the edge frame 310, the supportplate is coupled to an external surface of the edge frame 310. Thus,unlike in FIG. 5, where a circumscribing edge of the support plate, anedge that runs all the way around the support plate, contacts the edgeframe, in FIG. 8, the edges 333 of the support plate are exposed.

FIG. 9 illustrates a cross-sectional side view of an embodiment of anelectronic device housing 401 having an edge frame 410 with flatexternal surfaces. The housing 401 is substantially similar to thehousing 101 of FIG. 4; however, the edge frame 410 has flat externalsurfaces, rather than rounded external surfaces as illustrates by thehousing 101 of FIG. 4. The edge frame 410 may have other externalshapes.

FIG. 10 illustrates a cross-sectional view of an embodiment of anelectronic device housing 501 having a support plate 530 and a rearcover 560. The housing 501 is substantially similar to the housing 101of FIG. 4; however, the support plate 530 is interior to the housing 501and a rear cover 560 is set upon the rear bezel 119. The support plate530 is inset into the edge frame 510 and may be wider than the rearcover 560. The support plate 530 defines a front cavity 142 and a rearcavity 144. The support plate 530 may have through-holes by which thefront cavity 142 and the rear cavity 144 are coupled.

FIG. 11 illustrates a flowchart of a method of forming an electronicdevice. The method 600 begins, in block 610, by providing a edge frame.The edge frame may be, for example, the edge frame 110 of FIG. 1. Theedge frame may be lightweight and relatively elastic. In one embodiment,the edge frame has a thickness of 5 millimeters or greater, an elasticmodulus between 3 GPa and 15 GPa, and a density of 0.8 g/cc or less. Inone embodiment, the edge frame is composed of foam, such as closed-cellaluminum foam. Closed-cell aluminum foam may be created by injecting agas or mixing a foaming agent, such as titanium hydride (TiH₂) intomolten aluminum. The foam may have an average cell size of approximately0.5 mm or less. The foam may have a median cell size of approximately0.5 mm or less. The edge frame may be composed of other materials.

In block 620, a support plate is provided. The support plate may be, forexample, the support plate 130 of FIG. 1. The support plate may berelatively flat and stiff. In one embodiment, the support plate has athickness of 1 millimeter or less and an elastic modulus of 50 GPa orgreater. In one embodiment, the support plate is composed of a compositematerial, such as carbon-fiber reinforced polymer or aluminum metalmatrix composite. A composite material may be formed by embedding areinforcement material into a matrix or resin. In one embodiment, thesupport plate is formed by cutting or punching a shape from a sheet ofcomposite material. The support plate may be composed of othermaterials.

In block 630, the support plate is coupled to the edge frame to form ahousing. The support plate may be coupled to the edge frame by applyingan adhesive between the support plate and the edge frame and adjoiningthe support plate to edge frame. The support plate may be coupled to theedge frame by brazing the support plate to the edge frame. Thus, thesupport plate and the edge frame may be adjoined and molten metal drawnbetween them via capillary action. The support plate may be coupled tothe edge frame by thermal bonding. The support plate and the edge framemay be coupled using a fastener, such as a screw or bolt. The supportplate and the edge frame may be coupled mechanically via an interferencefit. The support plate and the edge frame may be coupled by othermethods. Forming the housing may include other steps and the housing mayinclude other portions. For example, the housing may further include afront cover.

In block 640, one or more electronic components are inserted into thehousing. The electronic components may include, for example, a printedcircuit board, conductive traces, a resistor, a switch, a diode, abattery, a processor, a memory or any other component. It is to beappreciated that the steps referred to in blocks 630 and 640 may beperformed simultaneously or overlapping. For example, the support platemay be coupled to the edge frame, the one or more electronic componentsinserted and the housing completed by a front cover or other housingcomponents.

The foregoing description sets forth numerous specific details such asexamples of specific systems, components, methods and so forth, in orderto provide a good understanding of several embodiments of the presentinvention. It will be apparent to one skilled in the art, however, thatat least some embodiments of the present invention may be practicedwithout these specific details. In other instances, well-knowncomponents or methods are not described in detail or are presented insimple block diagram format in order to avoid unnecessarily obscuringthe present invention. Thus, the specific details set forth are merelyexemplary. Particular implementations may vary from these exemplarydetails and still be contemplated to be within the scope of embodimentsof the present invention.

In the above description, numerous details are set forth. It will beapparent, however, to one of ordinary skill in the art having thebenefit of this disclosure, that embodiments of the present inventionmay be practiced without these specific details. In some instances,well-known structures and devices are shown in block diagram form,rather than in detail, in order to avoid obscuring the description.

It is to be understood that the above description is intended to beillustrative and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reading and understanding theabove description. The scope of the present invention should, therefore,be determined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

What is claimed is:
 1. An electronic device comprising: one or moreelectronic components; a housing defining a cavity in which the one ormore electronic components are disposed, wherein the housing comprises:a cover disposed at a first side of the cavity; a support plate disposedat a second side of the cavity, wherein the support plate comprises acomposite material; and an edge frame surrounding the cavity and coupledto the cover and the support plate, wherein the edge frame comprises afoam material, wherein the foam material has a density less than the adensity of the composite material and the composite material has astiffness greater than a stiffness of the foam material.
 2. Theelectronic device of claim 1, wherein the cover contacts a front bezelof the edge frame and wherein the support plate contacts a rear bezel ofthe edge frame.
 3. The electronic device of claim 1, wherein the edgeframe has a density of less than 0.8 grams per cubic centimeter and thesupport plate has an elastic modulus of greater than 50 gigapascals. 4.The electronic device of claim 1, wherein the cover comprises a displayscreen.
 5. The electronic device of claim 1, wherein the compositematerial of the support plate comprises at least one of a carbon-fiberreinforced polymer material or an aluminum metal matrix compositematerial.
 6. The electronic device of claim 1, wherein the foam materialof the edge frame comprises a closed-cell aluminum foam.
 7. Anelectronic device housing comprising: a substantially flat support platecomprising a composite material; and an edge frame comprising a foammaterial, wherein the edge frame is coupled to the support plate at aperimeter of the support plate and defines a cavity.
 8. The electronicdevice housing of claim 7, wherein the support plate has a thickness of1.0 millimeters or less.
 9. The electronic device housing of claim 7,wherein a width of the support plate is at least ten times as great as athickness of the support plate and wherein a thickness of the edge frameis at least five times a thickness of the support plate.
 10. Theelectronic device housing of claim 7, wherein the composite material ofthe support plate comprises at least one of carbon-fiber reinforcedpolymer or an aluminum metal matrix composite.
 11. The electronic devicehousing of claim 7, wherein the composite material of the support platehas an elastic modulus of at least 50 gigapascals.
 12. The electronicdevice housing of claim 7, wherein the foam material of the edge framecomprises closed-cell aluminum foam.
 13. The electronic device housingof claim 7, wherein the foam material of the edge frame has a density ofless than 0.8 grams per cubic centimeter.
 14. The electronic devicehousing of claim 7, wherein the edge frame comprises an interior portioncomposed of the foam material and an exterior portion at least partiallysurrounding the interior portion.
 15. The electronic device housing ofclaim 7, wherein the edge frame surrounds the support plate such that acircumscribing edge of the support plate contacts the edge frame. 16.The electronic device housing of claim 15, wherein the support plate isdisposed upon a bezel of the edge frame.
 17. An electronic devicehousing comprising: a substantially flat support plate; and an edgeframe coupled to the support plate at a perimeter of the support plateand defining a cavity, wherein the edge frame has a density less than adensity of the support plate and the support plate has a stiffnessgreater than a stiffness of the edge frame.
 18. The electronic devicehousing of claim 17, wherein a width of the support plate is at leastten times as great as a thickness of the support plate, and wherein athickness of the edge frame is at least five times a thickness of thesupport plate.
 19. The electronic device housing of claim 17, whereinthe support plate has an elastic modulus of 50 gigapascals or greaterand wherein the edge frame has an elastic modulus between 3 gigapascalsand 15 gigapascals and a density of 0.8 grams per cubic centimeter orless.
 20. The electronic device housing of claim 17, wherein the supportplate comprises at least one of a carbon-fiber reinforced polymermaterial or an aluminum metal matrix composite material, and the edgeframe comprises an aluminum foam material.